Insectifuge and insecticide



' insectifuges which are the subject of the inven-' Patented Feb. 16, 1937 insnc'rmoea ANDINSECTICIDE, Lowell B. Kilgore. Washington, D. c.

No Drawing. Application 12 Claims.

Thisinvention relates to a new composition of, matter which is repellentand toxic toward in-- sects, but is neither ofiensive nor poisonous to warm-blooded animals. v

This invention has forv its object the produc tion of insecticides, and insectifuges comprising synthetic organic chemicals having the highly desirable physiological properties of repelling insects from their presence and of killing insects when contacted thereby. The. insecticides and tion disclosed herein comprise'an admixture of one or more synthetic organic chemicals with a diluent suitable for their 'use as an insecticide and-as an insectifuge. Furthermore, by com-' bining one or more ofthe compounds described herein with botanical extractives," themselves toxic to'a greater or less degree to insects, the insecticidal and insectifugalvalues of such extractives are enhanced and stabilized.

, Specifically, I have discoveredthat the 'members of the classof organic compounds known as delta, epsilon-unsaturated, alpha, gamma,

. 4th edition,

diketo-carboxylic esters, and enol forms thereof (see Beilstein, Handbook of Organic Chemistry,

plement, vols. 3-4, page 266), when incorporated in a suitable diluent, produce-compositions which possess valuable insecticidal and insectifugal properties. The esters which are the subjectof acid by means of metallic sodium. The generic formula for this class of organic chemicals is represented by R: n l I R- C=CHC0'CH=C(OH)CO0R;= R: p R1 alpha form beta form This has recently been shown to be a case oi.' ring-chain isomerismrather'than one" of des-' motropism. The beta form shown above probably does'not exist-but is a dihydropyrone, the equilibrium being represented thus:

enol or alpha form lein end-point.

dihydropyrone tom anuary 3; 1936, Serial ,457

see: Dieckmann, as, 533, 1772 (1920);151eckmann and von Anwers, ibid.', 5613,1527 1923); Morton and Rogers, J Chem. $00., 1926, 713.

However, the earlier nomenclature whereby the compounds'are regarded as the beta or keto form is adhered to in this disclosure of my invention This nomenclaturenot only conforms to that used in the best ,known works ofrefer- .ence, butis convenient for identifying, the compounds herein disclosed by which they are made. i

As an example of what is meant by the nomenclature just referred to and used herein, I may cite the instance where R1, R2, and-Rrof the above structural formulae are all methyl radicals, giving according to this nomenclature mesityl-oxide oxalate, methyl ester Ann. 291, 111 (1890) represented CH: v

c=cH'co-cmcocoocm the components from This compound, according to the later evidence (see Dieckmann, etc., supra), actually exists. as

tw isomeric mpound represented by: ;pages763-5,-ibid., first sup- 7 I i hy C=IGH-COGH=G(OH)COOCBI=-OHI (L -coocm O on( 0 (2) Y r 1 one] or alpha form dihydropyrone form where (1) is the enol form of mesityl oxide oxalate, methyl ester and (2) is alpha, alpha-dimethyl alpha prime carbomethoxy dihydropyrone. In this particular case it is possible to prepare the isomers (1') and (2) in a pure condition whereby I have found that both are suitable for this invention. I

The approximate amount of the enol isomer present in .a mixture of the enol anddihydro- Dyrone isomers of a particular member of this (see Clai sen,

series may be determined by titrating a weighed amount of the mixture in an alcoholicsolution The validity of this titration method as a means of determining the amount of each isomer present in a mixture of the two, may be shown by the results obtained using pure, recrystallized isomers of known purity. This is possible in the instance of mesityl oxide oxalate, methyl ester wherein the two isomers can be prepared in a pure condition as shown above. (Claisen, loc. cit.) The results obtainedfor these pure. crystalline isomers togetherv with the results obtained by titrating other members of the series of estate referred to in this invention are shown below; The isomers have not been separated in the latter instances, urification of the samples having been eflected by vacuum distillation. Inasmuch as the compounds are regarded as probably existing wholly as sodium enolates in the reaction mixture in which they areproduced, their subsequent neutralization presumably produces the enol isomer which is gradually converted to the corresponding dihydropyrone under the influence of heat during their purification by distillation. The composition'of this distillate is therefore a mixture of the enol and dihydropyrone forms, the amount of each being dependent upon the character of the substituents as indicated in the general formula for the series:

(in R, I 0 R3 exist wholly in the enol form:

Percent Per- Oompound cent E25 pyrone Mesityl oxide oxalate, methyl ester (enol.) 99 0 Mesityl oxide oxalate, methyl ester (dihydropyrone .l. 1 99+ esityl oxide oxalate, ethylesternn- 8 92 Mesityl oxide oxalate, n-butyl ester. 14 .86 Mesityl oxide oxalate, iso-amyl ester. 23 77 Bete-ionone oxalate, ethyl ester 83 17 Benzalaoewne oxalate, n-butyl ester 103 0 The efficacy of the members of this series of chemicals, delta, epsilon-unsaturated, alpha. gamma-diketo carboxylic esters and. their isomers, as insect repellents is shown by the following experiments designed to test powers of the chemicals:

"Baits suitable for attracting house flies are prepared by coatingstrips of blotting paper with a glucose syrup. These strips are then individually treated under identical conditions with a spray made by dissolving the chemical, the insectifugal properties of which are to be tested,

the repellent in deodorized kerosene or a mixture of deodi zed kerosene and an auxiliary solvent, suchas, acetone. These treated baits together with one which had been treated with the solvent only, are then. mounted in a cage of hungry house flies. The arithmetical mean number of flies ester Furtural acetone oxalate, ethyl eaten-..

' epsilon-unsaturated, alpha, ganima-dilreto carboxylic esters and their, isomers, which I have found to be effective insectifuges from my researches and have given the results obtained by this method in the following Table Number 1.

Teens NUMBER 1 Insectifuge tests upon house flies by the bait method Concentretion Delta epsilon-unsaturated, alpha gammadiketo ester g mg kerosene Aver. no. on sample Mesityl oxide oxalate, methyl ester, enol isomer Mesityl..ox e oxalate, methyl ester,

dihydropyrone isomer Mesityl oxide oxalate, ethyl ester Mesgg'l oxide oxalate, normal propyl 0S Mesityl oxide oxalate, ieo-propyl ester. Mesityl oxide oxalate, normal butyl ester Mesitgl oxide oxalate, secondary buty es Mesityl oxide oxalate, iso-hutyl ester. Mesityl oxide oxalate, normal amyl ester Moagyl oxide oxalate, seco dary amyl Mesityl oxide oxalate, i'so-amyl ester Mesityl oxide oxalate, benzyl ester--- Mesityl oxide oxalate, cyclohexyl ester Benzal acetone oxalate, ethyl ester Benz-s1 acetone oxalate, normal butyl 8888 ibe'eas Crotonal acetone oxalate, ethyl ester..... Pseudo-ionone oxalate, ethyl ester p-Ionone oxalate, ethyl ester Mesityl oxide oxalate, trahydroiuriuryl ester Tears Nmusrm 2 photographs made at Insecticidal tests by the Peat-Grady method using a house flies Cone. P Delta 0 silon-unsatugm Per- Distrl- Probable rate'd, alpha, gamma- 2 53 cent bution percent diketo ester km down kill sigma kill sene Mesityl oxide oxalate,

ethyl ester "a 5 -85 -42 9.6 38.8-45.2 Banzai acetone oxalate,

ethyl ester 5 38 7 B-Ionone oxalate, ethyl aster 5 84 44 Pyrethrum extract, 1 lb./

gallon... 97 78 9.8 75.2-81.4 Sameextract+5percent l mesityl oxide oxalate, ethyl ester 98 89 1.2, 88.9-89.7

In addition to the insecticidal tests shown in Table 2, I have tested the following esters by an indirect fog procedure using house flies as the test insect and have insecticides Mesityl oxide oxalate, iso-propyl ester Mesityl oxide oxalate, iso-butyl ester Mesityl oxide oxalate, normal butyl ester Mesityl oxide oxalate, cy'clohexyl ester Mesityl oxide oxalate, secondary butyl ester Mesityl oxide oxalate, normal'amyl ester -As shown in the tables I have given from my researches both the insectifugal and the insecticidal properties of this which vary in value with the character of the infound them to be eifective class of synthetic esters.

dividual substituents made in accordance with the generic formula.

While I have in the above description of my invention disclosed a number of preferred and wherein R1 and R2 are either the same or different organic radicals or respectively one organic radical and one hydrogen atom, and R3 is any organic radical or group forming an ester of the carboxyl group.

2. An insectifuge or insecticide comprising a 6,e-unsaturated-a,' -diketo carboxylic ester of the general formula,

40 the same being the enol tautomer of the corresponding diketo ester, and wherein R1 and R2 are eitherthe same or different organic radicals, or respectively, one organic radical and one hydrogen atom, and wherein R3 is any organic radical 45 forming an ester with the carboxyl group.

3. An insectifuge or insecticide comprising an ester of an a,a-disubstituted-u'-carboxy-dihydro- 'y-pyrone of the general formula,

C -0 0 O R:

normal propyl ester; mesityl oxide oxalate, isopropyl ester; mesityl oxide oxalate, normal butyl ester; mesityl oxide oxalate, secondary butyl ester; mesityl oxide oxalate, iso-butyl ester; mesityl oxide oxalate, normal amyl ester; mesityl oxide oxalate, secondary amyl ester; mesityl oxide oxalate, iso-amyl ester; mesityl oxide oxalate, benzyl ester; mesityl oxide oxalate, cyclohexyl ester; mesityl oxide oxalate, tetrahydrofurfuryl 75 ester; benzal acetone oxalate, ethyl ester; benzal a practical embodiments of my invention, it will i acetone oxalate, normal butyl-- ester; furfural acetone oxalate, ethyl ester; crotonal acetone oxalate, ethyl ester; pseudo-ionone oxalate, ethyl ester; fl-ionone oxalate, ethyl ester.

5. An insectifuge or insecticide comprising in solution, a mixture of the enol isomer of a 6,241!)- saturated-a,'y-diketo carboxylic ester and an ester of an a, x-disubstituted-a'-carboxydihydro-v-pyrone of the general formula:

wherein R1 and R2 are either the same or different organicradicals or respectively one organic radical and one hydrogen atom, and R3 is any organic radical or group forming an ester of the'carboxyl group.

.6. An insectifuge or insecticide comprising in solution, a li -unsaturated-a,'y-diketo carboxylic ester of the general formula,

o=cH-oocH=c(o11)oooR.

the same being the enol tautomer of the corresponding diketo ester, and wherein R1 and R2 are either the same or different organic radicals, or

respectively one organic radical and one hydrogen atom, and wherein R3 is any organic radical forming an ester with the carboxyl group.

7. An insectifuge or insecticide comprising in solution, an ester of the a',e-disubstituted, a'carboxydihydro-y-pyrone of the general formula,

wherein R1 and R2 are either the same or different organic radicals, or respectively one organic radical and one hydrogen atom, and R3 is any organic radical forming an ester with the carboxyl group.

8. An insectifuge or insecticide comprising in solution, a synthetic ester selected from the group consisting of mesityl oxide oxalate, methyl ester, enol isomer; mesityl oxide oxalate, methyl ester, dihydropyrone isomer; mesityl oxide oxalate, ethyl ester; mesityl oxide oxalate, normal propyl ester; mesityl oxide oxalate, iso-propyl ester; mesityl oxide oxalate, normal butyl ester; mesityl oxide oxalate, secondary butyl ester; mesityl oxide oxalate, iso-butyl ester; mesityl oxide oxalate, normal amyl ester; mesityl oxide oxalate, secondary amyl ester; mesityl oxide oxalate, iso-amyl ester; mesityl oxide oxalate, benzyl ester; mesityl oxide oxalate, cyclohexyl ester; mesityl oxide oxalate, tetrahydrofurfuryl ester; benzal acetone oxalate, ethyl ester; benzal acetone oxalate, normal butyl ester; furfural acetone oxalate, ethyl ester; crotonal acetone oxalate, ethyl ester; pseudo-icnone oxalate, ethyl ester; p-ionone ethyl ester.

9. An insectifuge or insecticide in solution, of a strength of from 2 to 5 percent of a mixture of the enol isomer of a 6,e-unsaturated,,'ydiketo carboxylic ester and an ester of an 1,11-

general formula:

4 disubstituted-u-carboxydihydro-'y-pyrone or the organic radicals or respectively one organic radical and one hydrogen atom, and R3 is any organic radical or group forming an ester of the carboxyl group.

10. An insectifuge or insecticide comprising in solution of a strength of from 2 to 5 percent of a -ae-unsaturated-a, -diketo carboxylic ester of the general formula:

\C=CH-COCH=C(OH)COOR the same being the enol tautomer of'the corresponding diketo ester, and wherein R1 and R2 are either the same or different organic radicals, or respectively one organic radical and one hydrogen atom, and wherein R3 is any organic radical forming an ester with the carboxyl group.

11. An insectifuge or insecticide comprising in solution of a strength of from 2 to 5 percent of an ester of an a',a-dlSubStltl1t8d, t'carboxy-dihydro-' -pyrone of the general formula,

hydropyrone isomer; mesityl oxide oxalate, ethyl ester; mesityl oxide oxalate, normal propyl ester; mesityl oxide oxalate, iso propyl ester; mesityl oxide oxalate, normal butyl ester; mesityl oxide oxalate, secondary butyl ester; mesityl oxide oxalate, iso-butyl ester; mesityl oxide oxalate,

normal amyl ester; mesityl oxide oxalate, secondary amyl ester; mesityl oxide oxalate, iso-amyl ester; mesityl oxide oxalate, benzyl ester; mesityl oxide oxalate, cyclohexyl' ester; mesityl oxide oxalate, tetrahydrofurfuryl ester; benzal acetone oxalate, ethyl ester; benzal acetone oxalate, norester; crotonal acetone oxalate, ethyl ester; pseudo-ionone oxalate, ethyl ester; p-ionone oxalate, ethyl ester LOWELL B. KILGORE.

' mal butyl ester; furi'ural acetone oxalate, ethyl 

